The present invention relates to hydrophobic, oil-absorbing polymeric compositions for transferring oily substances and hydrophobic materials to and from various surfaces in a heterogeneous medium. In particular, the invention is directed to a reversible process for transferring oily substances and hydrophobic materials from various surfaces in a heterogeneous medium using oil-absorbing films, solid particles or dispersions of aqueous emulsion polymers prepared from hydrophobic monomers.
The removal of oils, greases, protein based stains and odors from textiles, fabrics, hard surfaces, skin, pharmaceuticals, animal products, liquids, air and the environment using a single class of polymeric materials is desirable. In addition, the removal or transfer of such materials from surfaces in a heterogeneous medium is also desired. Oil-absorbing polymeric materials are broadly divided into two classes, one class comprising synthetic high-molecular weight polymers and the other class comprising naturally occurring polymeric materials. Examples of the former class of materials are polypropylene, polystyrene, polyurethane foam, polymethyl(meth)acrylate, and polyacrylic acid. Examples of the latter class of materials are pulp fibers, cotton fibers, cellulose, modified celluloses, starches, dextrins and gums. However, materials from both classes have a somewhat narrow range of oil-absorbing efficiencies and/or limited capacities to function as oil-absorbing materials, which is due in part to polymer composition and to the physical form of the material. For example, it is difficult to achieve the physical combination of an oil-absorbing solid suspended in water with an oily substance soaked in to a substrate, such as a fabric, with the result that the oily substance is transferred in the heterogeneous medium to the solid.
U.S. Pat. No. 4,940,578 and European publication EP 0 295 903 disclose a hair preparation comprising a squalene-absorbing, polymeric composition prepared from a vinyl monomer which helps to reduce the greasiness of hair and scalp. However, there remains a need for alternative polymeric materials which have superior oil absorbing properties, both for naturally occurring oils and synthetic oils, and which is effective at removing oily substances from textiles, hard surfaces, oil/water emulsions, multiphasic media and other environments. Moreover, polymeric materials having the ability to absorb oily substances as well as providing a means for transporting them from various surfaces in a heterogeneous medium are still sought. A process using an oil-absorbing polymeric composition for the removal of oils and greases from surfaces would, therefore, be of great utility to the commercial manufacture of detergents, cosmetics, cleaners, personal care products and environmental oil-absorbing materials.
The inventors have discovered, surprisingly, a class of polymer compositions prepared from hydrophobic monomers that facilitate the removal of oily substances and hydrophobic materials in a heterogeneous medium beyond the capability of current oil-absorbing polymer compositions. A hydrophobic, oil-absorbing polymer composition has been discovered that has the ability to absorb at least 20 weight percent of an oily substance or hydrophobic material based on the total weight of the polymeric composition. In adddition, the inventors have discovered reversible processes, using the hydrophobic polymer compositions, for removing, transferring or transporting oily substances and hydrophobic materials from a variety of substrates and surfaces in a heterogeneous medium.
In a first aspect of the present invention there is provided an oil-absorbing polymer composition of Formula 1: 
wherein A is a polymerized residue of (meth)acrylic acid; B is a polymerized residue of a monomer selected from one or more C8-C24 alkyl (meth)acrylates; C is a residue of a monomer selected from one or more C1-C24 alkyl (meth)acrylates; and wherein the polymer composition, in the form of solid particles, a film or a dispersion, absorbs at least 20 weight percent of an oily substance or hydrophobic material in a heterogeneous medium based on the total weight of the polymeric composition.
In a second aspect of the present invention there is provided a process for removing an oily substance or hydrophobic material from a surface of a substrate in a heterogeneous medium including the steps of directly contacting the surface of the substrate containing an oily substance with the oil absorbing polymer composition, in the form of solid particles, a film or a dispersion; allowing the polymer composition to absorb the oily substance or hydrophobic material; and removing the swollen oil-containing polymer composition from the medium.
In a third aspect of the present invention there is provided a process for removing an oily substance or hydrophobic material from a substrate in a heterogeneous medium including the steps of combining a substrate containing an oily substance, the oil-absorbing polymer composition in the form of a dispersion and, optionally, a carrier composition or complexation agent to facilitate transport in the medium; allowing the polymer composition to absorb the oily substance or hydrophobic material; and separating the swollen oil-containing polymer composition from the medium.
The oil-absorbing polymer composition usefully employed in accordance with the present invention is prepared from a combination of an ionic monomer and one or more hydrophobic monomers, which results in a polymer composition having the formula: 
wherein A is a polymerized residue of (meth)acrylic acid; B is a polymerized residue of a monomer selected from one or more C8-C24 alkyl (meth)acrylates; C is a residue of a monomer selected from one or more C1-C24 alkyl (meth)acrylates. xe2x80x9cPolymerized residuexe2x80x9d refers to monomer units A, B and C. A, B and C residues are randomly arranged in said polymer. S and T represent initiators and chain transfer residues, respectively. R represents H, CH3 or an alkyl group. The term xe2x80x9cmxe2x80x9d represents the total number of A residues and ranges from 1 to 20, preferably 1 to 5, most preferably 1 to 3. The preferred weight percent of monomer units of A ranges from to 0.01 to 5. The term xe2x80x9cnxe2x80x9d represents the total number of B residues and is  greater than 1. The preferred weight percent of monomer units of B ranges from to 5-95, depending on the weight percent of monomer units of C. The term xe2x80x9cpxe2x80x9d represents the total number of C residues and is  greater than 1. The preferred weight percent of monomer units of C ranges from to 5-95, depending on the weight percent of monomer units of B.
The oil-absorbing polymer composition is prepared as a terpolymer although compositions containing more than three monomer residues are contemplated. In a preferred embodiment, the oil-absorbing polymer composition, usefully employed in accordance with the present invention, is a terpolymer, wherein monomer A is a residue of (meth)acrylic acid, monomer B is a residue selected from C8-C20 alkyl (meth)acrylates, and monomer C is residue selected from C1-C24 alkyl (meth)acrylates, S and T represent initiators and chain transfer residues, respectively. In another preferred embodiment, the oil-absorbing polymer composition is a terpolymer, wherein monomer A is a residue of (meth)acrylic acid, monomer B is a residue selected from C12-C20 alkyl (meth)acrylate monomer, and monomer C is methyl (meth)acrylate, S and T represent initiators and chain transfer residues, respectively. The terpolymer is prepared from relatively high levels (as wt %) of hydrophobic monomers and relatively low levels (as wt %) of ionic monomers in the form of (meth)acrylic acid or acrylic acid in a wide range of weight average molecular weight, Mw. The terpolymer includes from 80% to 98% by weight of a combination of hydrophobic monomers in the form of C4-C24 alkyl (meth)acrylates and from 0.01% to 20% by weight of ionic monomers. Preferably, the terpolymer includes from 90% to 99.99% by weight of a combination of hydrophobic monomers in the form of C4-C24 alkyl (meth)acrylates and from 0.01% to 10% by weight of ionic monomers in the form (meth)acrylic acid. More preferably, the terpolymer includes up to 98% by weight of a combination of hydrophobic monomers in the form of C4-C24 alkyl (meth)acrylates and from 1% to 3% by weight of (meth)acrylic acid. The term xe2x80x9calkyl (meth)acrylatexe2x80x9d refers to either the corresponding acrylate or methacrylate ester. Similarly, the term xe2x80x9c(meth)acrylicxe2x80x9d refers to either acrylic acid or methacrylic acid and its corresponding derivatives, such as esters or amides.
The weight average molecular weight of the backbone, as measured on the polymer product after exhaustive hydrolysis, consisting of polymerized units of A, B and C, ranges from 300 to 600,000. Preferably, weight average molecular weights range from 1000 to 100,000. In terms of oil-absorbing capacity, oil-absorbing polymer compositions having weight average molecular weights ranging from 100,000 to 600,000 are preferred. In terms of removing and transporting the swollen oil-containing polymer composition from a heterogeneous medium, oil-absorbing polymer compositions having weight average molecular weights ranging from 300 to 100,000 are preferred. Weight average molecular weights were measured using gel permeation chromatography (GPC) with styrene as a standard and are expressed as weight average molecular weight.
Monomers suitable for the oil-absorbing polymer composition and its use in the novel processes of the present invention include hydrophobic and ionic monoethylenically unsaturated monomers which can be subjected to free radical polymerization in a straight forward manner using standard emulsion polymerization techniques. xe2x80x9cIonic monomersxe2x80x9d refer to monoethylenically unsaturated monomers which are water soluble under the conditions of emulsion polymerization, as described in U.S. Pat. No. 4,880,842. As used herein, the term xe2x80x9cwater solublexe2x80x9d, as applied to monomers, indicates that the monomer has a solubility of at least 1 gram per 100 grams of water, preferably at least 10 grams per 100 grams of water and more preferably at least about 50 grams per 100 grams of water. xe2x80x9cHydrophobic monomersxe2x80x9d refer to monoethylenically unsaturated monomers which have low or very low water solubility under the conditions of emulsion polymerization, as described in U.S. Pat. No. 5,521,266. As used herein, monomers having xe2x80x9clow water solubilityxe2x80x9d or xe2x80x9cvery low water solubilityxe2x80x9d refers to monoethylenically unsaturated monomers having a water solubility at 25-50xc2x0 C. of no greater than 200 millimoles/liter water or 50 millimoles/liter water, respectively, and the hydrophobic monomers employed in this invention are monomers having low water solubility. The resulting oil-absorbing polymer compositions that are employed in this invention have low to very low water solubility. The advantages of both the oil-absorbing polymer and its use in the novel processes of the invention are realized when the oil-absorbing polymer composition includes relatively large amounts of hydrophobic monomers compared to relatively small amounts of ionic monomers.
Suitable monomer units of A are ionic monomers that include monoethylenically unsaturated mono carboxylic acids such as for example, acrylic acid (AA), methacrylic acid (MAA), alpha-ethacrylic acid, xcex2,xcex2-dimethyl acrylic acid, vinyl acetic acid, allyl acetic acid and alkali and metal salts thereof. Methacrylic acid is preferred.
Suitable monomer units of B and C are hydrophobic monomers that include one or more C1-C24 alkyl (meth)acrylates or C1-C24 alkyl acrylates. Suitable alkyl (meth)acrylates or alkyl acrylates include for example methyl (meth)acrylate, ethyl acrylate (EA), isopropyl (meth)acrylate, butyl acrylate(BA), butyl (meth)acrylate (BMA), 2-ethyl hexyl acrylate, benzyl (meth)acrylate, octyl acrylate, decyl acrylate, lauryl acrylate, behenyl acrylate, lauryl (meth)acrylate (LMA), oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate (SMA), behenyl (meth)acrylate, cetyl(meth)acrylate, eicosyl(meth)acrylate; blends of C10-C24 alkyl (meth)acrylates, such as cetyl-eicosyl (meth)acrylate (CEMA); aromatic and alkyl aromatic esters of (meth)acrylic acid; and unsaturated vinyl esters of (meth)acrylic acid such as those derived from fatty acids and fatty alcohols and combinations thereof. Preferably, monomer units of B are lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, behenyl (meth)acrylate, stearyl (meth)acrylate, cetyl(meth)acrylate, eicosyl(meth)acrylate. Preferably, monomer units of C are methyl(meth)acrylate, ethyl acrylate (EA), isopropyl (meth)acrylate, butyl acrylate, butyl (meth)acrylate, 2-ethyl hexyl acrylate, benzyl (meth)acrylate, octyl acrylate, decyl (meth)acrylate, behenyl (meth)acrylate and lauryl (meth)acrylate.
The oil-absorbing emulsion polymers compositions usefully employed in accordance with the present invention are prepared from relatively high levels of hydrophobic monomers and relatively low levels ionic monomers using the methods described in U.S. Pat. Nos. 4,797,223; 4,404,309; 5,008,329, 5,521,266; 6,040,409 6,063,857 and European publication EP 0 989 163 A1. The process for preparing an aqueous emulsion, oil-absorbing polymer of this invention includes providing one or more hydrophobic, ethylenically unsaturated monomers, an ionic monomer and a free radical redox initiator system under emulsion polymerization conditions. The preparation of blends of two or more oil-absorbing polymers are also usefully employed in accordance with the present invention.
In another aspect of the present invention the oil-absorbing polymer composition may be prepared by a multistage emulsion polymerization process, in which at least two stages differing in composition are polymerized in sequential fashion. Such a process usually results in the formation of at least two mutually incompatible polymer compositions, thereby resulting in the formation of at least two phases within the polymer particles. Such particles are composed of two or more phases of various geometries such as, for example, core/shell or core/sheath particles, core/shell particles with shell phases incompletely encapsulating the core, core/shell particles with a multiplicity of cores, and interpenetrating network particles. In all of these cases the majority of the surface area of the particle will be occupied by at least one outer phase and the interior of the particle will be occupied by at least one inner phase. Each of the stages of the multi-staged emulsion polymer may contain the same monomers, surfactants, chain transfer agents, etc. as disclosed herein-above for the emulsion polymer. The polymerization techniques used to prepare such multistage emulsion polymers are well known in the art such as, for example, U.S. Pat. Nos. 4,325,856; 4,654,397; and 4,814,373.
S and T residues are derived from one or more initiator radicals and one or more chain transfer agents, respectively, as described in U.S. Pat. No. 5,521,266. Optionally, groups capable of undergoing cross-linking reactions may be grafted onto the backbone via a radical reaction. A free radical initiator or redox initiator (S) is used in the aqueous solution and emulsion polymerizations. Suitable free radical initiators include for example hydrogen peroxide; tert-butyl hydroperoxide; t-amyl hydroperoxide; sodium, potassium, lithium and ammonium persulfate. Suitable reducing agents include for example bisulfite and its salts, metabisulfite and its salts, sodium formaldehyde sulfoxylate and reducing sugars such as ascorbic acid may be used in combination with the initiar to form a redox system. The amount of initiator may be from 0.01% by weight to about 2% by weight of the monomer charged and in a redox system, a corresponding range of 0.01% by weight to about 2% by weight of a reducing agent may be used. Optionally, transition metal catalysts, such as iron salts, may be used. Typical chain transfer agents (T) having high or low water solubility include for example hydrophobic mercaptans, such as n-dodecyl mercaptan; thiophenol; hydrophobic polymercaptans; hydrophobic halogen compounds, such as bromotrichloromethane and the like or mercaptoethanol and aminoethylenethiol.
Surfactants and organic solvents may be present during the polymerization of the ionic and hydrophobic monomers used to prepare the oil-absorbing polymer composition. It is preferred the oil-absorbing polymer compositions are prepared without the use of organic solvents or high levels of surfactants. Moreover, the oil-absorbing, hydrophobic polymer compositions are prepared from high levels of hydrophobic monomers in the presence of a complexation agent or phase transfer agent. Suitable complexation or phase transfer agents include for example xcex1-cyclodextrin, xcex2-cyclodextrin, xcex3-cyclodextrin and cyclodextrin derivatives such as methyl-xcex2-cyclodextrin, crown ethers, and the like.
The oil-absorbing polymer composition may include cross-linking agents to build polymer molecular weight and to produce modified polymer structures/conformations. Suitable cross-linking agents include for example allyl (meth)acrylate, ethylene glycol di(meth)acrylate (EGDMA), butylene glycol di(meth)acrylate (BGDMA), methylene bisacrylamide, pentaerythritol, di-, tri- and tetra-acrylates, divinyl benzene, polyethylene glycol diacrylates and bisphenol A diacrylates.
The oil-absorbing emulsion polymer compositions of the present invention have an average particle diameter that ranges from 20 nm to 1000 nm, preferably from 100 nm to 600 nm. Particle sizes herein are those determined using a Brookhaven Model BI-90 particle sizer manufactured by Brookhaven Instruments Corporation, Holtsville N.Y., and polymer particle diameters are reported as xe2x80x9ceffective diameter. Also contemplated are multimodal particle size oil absorbing emulsion polymers wherein two or more distinct particle sizes of or very broad distributions are provided as described in U.S. Pat. Nos. 5.340,858; 5,350,787; 5,352,720; 4,539,361 and 4,456,726.
The oil-absorbing polymer compositions of the present invention may be used as prepared (in slightly acidic form) or the acidic groups (xcx9c1 to 3%) may be neutralized to form salts containing carboxylate anions. Preferred alkali metal ions typically include sodium or potassium, alkaline earth metal cations such as magnesium and calcium, ammonium or tetra-alkyl ammonium salts, such as tetra methyl ammonium, or organic amine salts, such as the salts of tri-C1-C4 alkyl amines, hydroxy ethyl amines, or the mono-, di- or tri-C1-C4-alkanolamines, or mixtures thereof.
The oil-absorbing polymer composition usefully employed in accordance with the present invention may be used in the form of a solid, such as a spray dried or freeze dried powder, granules or film, and in liquid form as a water-borne latex dispersion. The oil absorbing polymer composition may be co-granulated or formulated with an inorganic carrier. Suitable examples of an inorganic carrier include for example alkali metal silicates, carbonates, sulfates, aluminosilicates and phosphates. Preferably, the polymer composition is usefully employed as an aqueous or co-solvent based dispersion.
In a second aspect of the present invention there is provided a process for removing an oily substance or hydrophobic material from a surface of a substrate in a heterogeneous medium including the steps of directly contacting the surface of the substrate containing an oily substance with the oil-absorbing polymer composition, in the form of solid particles, a film or a dispersion; allowing the oil-absorbing polymer composition to absorb the oily substance or hydrophobic material; and removing the swollen oil-containing polymer composition from the medium. xe2x80x9cHeterogeneous mediumxe2x80x9d refers to any closed system having two or more different phases of matter or two or more immiscible solvents in a liquid phase. Heterogeneous media include, but are not limited to for example a water-oil emulsion, an oil-water emulsion, a solid substrate containing a oily substance or hydrophobic material in water, an aqueous latex dispersion of the oil absorbing polymer composition and a solid substrate, a solid substrate saturated with an oily substance in water, any aqueous cleaning system employing the oil-absorbing polymer, any dry cleaning system employing the oil-absorbing polymer, any solvent based cleaning system, any cosmetic delivery system such as a polymer strip, compacted powder, and microsponge, any surface cleaning system employing the oil-absorbing polymer, any filtration system employing the oil-absorbing polymer, any bi-phasic extraction system, any organic compound dispersed in water or a solvent and any multi-component or multi-phase solvent system.
Direct contact of the oil-absorbing emulsion polymer composition usefully employed in the process of the invention with the oily surface can be effected with the composition in one of several forms in the following way including for example i) directly applying a neutralised solution containing the oil-absorbing polymer to the oily substrate surface; ii) directly applying the oil-absorbing polymer as prepared to the oily substrate surface; iii) contacting the oily substrate surface with a neutralised or as supplied solution of the oil-absorbing polymer; iv) contacting the oily substrate surface with the oil-absorbing composition in the form of a film; and v) contacting the oily substrate surface with the oil-absorbing composition in the form of freezed-dried or solid particles. Direct contact refers to any means of applying the oil-absorbing polymer to the oily substrate surface including for example coating, dabbing, spraying sponging, wiping and dipping in a pre-soaking surface treatment.
Through direct contact, the oily substance or hydrophobic material is apparently transferred from the substrate to the oil-absorbing polymer causing the oily substance or hydrophobic material to swell in to the oil-absorbing polymer to afford an oil-containing emulsion polymer composition. The process is reversible in that the oil-containing emulsion polymer composition can transport or release the oily substance or hydrophobic material to the surface of a different substrate. Transport may be effected by for example a complexation agent such as a cyclodextrin while release or transfer may be effected by for example a mechanical force, diffusion, and mechanical agitation.
Oily substances or hydrophobic materials effectively transported or removed from substrates using the oil-absorbing polymer process include for example body oils such as sebum and squalene, proteins, protein containing substances such as food, blood, fat; lipids, fatty acids, waxes, mineral oils, silicone oils, motor oils, crude oils, organic compounds, lipophilic toxins such as PCB, pesticides, insecticides, and herbicides; greases and vegetable oils. The oil-absorbing polymer process has utility in transferring or removing oily substances from surfaces of substrates including for example textiles, fabric, hard surfaces such as ceramics, wood, tile asphalt, cement; human skin, animal skin. Moreover, the oil-absorbing polymer compositions can be usefully combined or formulated with detergents such as those used in the home, industrially or in the environment; cleaners, personal care products such as hair and body washes and cosmetics, medical or pharmaceutical products.
In a third aspect of the present invention there is provided a process for removing an oily substance or hydrophobic material from a substrate in a heterogeneous medium including the steps of combining a substrate containing an oily substance, the oil-absorbing polymer composition in the form of a dispersion and, optionally, a carrier composition or complexation agent to facilitate transport in the medium; allowing the oil-absorbing polymer composition to absorb the oily substance or hydrophobic material; and separating the swollen oil-containing polymer composition from the medium.
The process usefully employed with this aspect of the invention includes combining the oil-absorbing polymer composition with another composition including for example a cleaner such as a detergent, a personal care product such as a cosmetic and a filtration system such as an air filter so that the oil-absorbing polymer contacts the substrate surface in the heterogeneous medium through an indirect process. The process also includes impregnating the oil-absorbing polymer composition on a carrier, which includes, but is not limited to, plastics sheets, cosmetic strips, fibers, textiles, filter materials and paper products.
The novel oil-absorbing polymer compositions and processes have utility in a wide variety of products including, but not limited to, for example household products such as laundry spot pre-treatments in the form of liquids, gels, solid sticks and spray-on, liquid and powder laundry detergents, dish washing and automatic dishwasher detergents, laundry bars, general purpose hard surface cleaners, floor cleaners, oven cleaners, odor control products, carpet/upholstery cleaners; personal care products such as microsponges or polyethylene sheets for facial oil removal, anti-aging skin care, anti-wrinkle cream, shampoos, hair washes, hair treatments, hair preparations, skin treatments, skin preparations, body washes, liquid and bar facial soaps, acne cleansing pads and general purpose cleaning pads or wipes, moisturizing creams, lotions and foundations, deodorants in body oils and odor absorbents, silicon replacements, makeup and foundations to absorb or release natural oils; medical and pharmaceutical products; extraction of toxins, absorption, transportation and release of hydrophobic materials; industrial products such as filtration systems for air and water, cleansing and odor control, (cigarette filters), floor coatings for non or low gloss, matte finish floors, (tiles, stones and non resilient substrates), general and floor cleaning in apartments, hospitals, hotels, restaurants and commercial businesses, environmental oil spills and toxic waste clean up of finely dispersed materials, vehicle and transportation cleaner/garage oil spill clean up, pitch control in paper machines to remove organic impurities, oil production-removal of residual oil contaminant, oil drilling fluids, food extraction (cholesterol from eggs), and paper products to hold or absorb printer ink (non-smudging).